Roosters losing feather around the head

Ok folks, I need some help. I had a rooster in one of the floor pens in our barn with six of seven hens. He started losing feathers at the top of his head. He finially lost almost all of them down to his neck. Where the loss is, he could not reach. Anyway, I let him out and put in another rooster and now the same thing is happening to the second one! When I look close they are thinning and it does look like something is eating the feathers. I have read about depluming mites and it says that they do not eat feathers. I use DE regularly on the birds and litter.
What could it be and how do I treat it?